The present disclosure relates to a vibration generating apparatus.
Such a vibration generating apparatus, converting electrical energy into mechanical vibrations using the principle of the generation of electromagnetic force, has commonly been mounted in mobile phones, and the like, to thereby be used for silently notifying a user of call reception by transferring vibrations thereto. In addition, in accordance with the rapid growth in the market for mobile devices such as the mobile phone, and the like, and the trend for the addition of added functionality to mobile devices, the mobile devices have been required to be relatively small in terms of size while having high quality. In this situation, the demand for the development of a vibration generating apparatus having a novel structure capable of overcoming the disadvantages of existing vibration generating apparatuses and having significantly improved quality has increased.
Further, as the release of smartphones, among mobile phones, has rapidly increased, a touchscreen user interface scheme has been adopted for use therein, such that a vibration motor has been used in order to generate vibrations at the time of a touch interaction with a touchscreen. Levels of performance required in the vibrations generated at the time of a touch interaction with such a touchscreen are as follows. First, since the amount of vibrations generated by a vibration generation apparatus is greater in the case of vibrations generated in response to a touch interaction with a touchscreen than in the case of vibrations generated at the time of call reception, the operational lifespan of a vibration generation apparatus should be extended. Second, in order to raise user's satisfaction when a user feels the vibrations at the time of touching the touchscreen, a response speed of the vibrations should increase in accordance with a touch speed of the touchscreen.
A piezo haptic actuator has been used as a product capable of implementing such features. Such a piezo haptic actuator uses the principle of an inverse piezoelectric effect in which displacement is generated when a voltage is applied to a piezo element, that is, a principle of allowing the weight of a mass body to be moved by the generated displacement to generate vibrational force.
A vibrator having the above-mentioned structure has the following features. A bandwidth of a frequency capable of obtaining a predetermined level of vibrational force or more is wide, such that stable vibration characteristics may be implemented, and vibrations having high and low frequencies, rather than a single frequency, within a predetermined frequency range may be variously used. In addition, since the vibrator may implement rapid operation response characteristics, it may be appropriate for implementing haptic vibrations in a mobile device such as a mobile phone, or the like.
However, the piezo element may be easily damaged due to external impacts. In other words, in the case in which the piezo element is disposed on a lower surface of an elastic plate of the mass body, the piezo element may be easily damaged due to a contact between the piezo element and a lower case when an external impact is applied to the vibrator.